Abstract: A band division process including a Fourier transformation is performed for an inputted speech signal, thereby outputting spectrum signals of plural channels. A cepstrum analysis process is performed for the spectrum signals, and a peak of the obtained cepstrum is detected in response to the cepstrum analysis result. Thereafter, a speech signal interval the inputted noisy speech signal is detected in response to the detected peak, and a noise is predicted in the speech signal in response to the detected speech signal interval. Then, the predicted noise is canceled in the spectrum signals thereby outputting noise-suppressed spectrum signals. Finally, the noise-suppressed spectrum signals are combined and are inverse Fourier-transformed, thereby outputting a noise-suppressed speech signal.

Abstract: A noise signal prediction system includes a signal detector for receiving a mixed signal having a voice signal and a background noise signal and for detecting the presence and absence of the voice signal contained in the mixed signal. A noise level detector is provided for detecting an actual noise level at each sampling cycle during the absence of the voice signal. A storing circuit stores the noise levels for a predetermined number of past sampling cycles. A predicting circuit predicts a noise level of a next sampling cycle based on the stored noise levels in the storing circuit. The storing circuit receiving and stores the actual noise levels during the absence of the voice signal, but stores the predicted noise levels during the presence of the voice signal.

Abstract: A noise suppression apparatus includes a tuner 1 which selectively receives a radio wave signal and transforms it into an electric signal H(k) , a field information detector 2 which detects electric field information of the radio wave signal received by the tuner 1, a noise data generator 6 which generates a noise pattern W(k) on the basis of the electric field information detected by the field information detector 2, a noise canceler 4 which removes an noise component from the signal outputted from the tuner 1, and an amplifier 7 which outputs a noiseless signal outputted from the noise canceler 4. The noise canceler 4 obtains a power spectrum .vertline.X(k).vertline..sup.2 on the basis of the signal H(k) fed from the tuner 1. Thereafter, the noise canceler 4 obtains a noise cancel signal S(k) on the basis of the values of the signal H(k), the noise pattern W(k), and the power spectrum .vertline.X(k).vertline..sup.2.

Abstract: A noise suppression apparatus comprising a tuner 1 which selectively receiving a radio wave signal to be received and transforming it into an electric signal, a field information detector 2 which detects electric field information of the radio wave signal received by the tuner 1, a noise data generator 6 which generates a noise pattern on the basis of the electric field information .detected by the field information detector 2, a noise canceler 4 which removes an noise component from the signal outputted from the tuner 1 on the basis of the noise pattern generated by the noise data generator 6, and an amplifier 7 which outputs a noiseless signal outputted from the noise canceler 4.

Abstract: A band division process including a Fourier transformation is performed for an inputted speech signal, thereby outputting spectrum signals of plural channels. A cepstrum analysis process is performed for the spectrum signals, and a peak of the obtained cepstrum is detected in response to the cepstrum analysis result. Thereafter, a speech signal interval of the inputted noisy speech signal is detected in response to the detected peak, and a noise is predicted in the speech signal in response to the detected speech signal interval. Then, the predicted noise is canceled in the spectrum signals thereby outputting noise-suppressed spectrum signals. Finally, the noise-suppressed spectrum signals are combined and are inverse Fourier-transformed, thereby outputting a noise-suppressed speech signal.

Abstract: A noise signal prediction system includes a signal detector for receiving a mixed signal having a voice signal and a background noise signal and for detecting the presence and absence of the voice signal contained in the mixed signal. A noise level detector is provided for detecting an actual noise level at each sampling cycle during the absence of the voice signal. A storing circuit stores the noise levels for a predetermined number of past sampling cycles. A predicting circuit predicts a noise level of a next sampling cycle based on the stored noise levels in the storing circuit. The storing circuit receiving and stores the actual noise levels during the absence of the voice signal, but stores the predicted noise levels during the presence of the voice signal.

Abstract: A voice signal coding system includes a voice signal detector for receiving a mixed signal of an intermittent voice signal and background noise signal and for detecting the presence and absence of the voice signal contained in the mixed signal. A voice signal period detector is provided for detecting a voice signal period in which the voice signal is present. A coding period control circuit is coupled to the voice signal period detector for producing a coding period control signal during the voice signal period. A coding circuit receives and encodes the mixed signal in response to the coding period control signal. Thus, the mixed signal is coded in the coding circuit only during the voice signal periods.

Abstract: A voice signal processor features a particular improvement of the S/N ratio. In the voice signal processor, the signal level in the voice band of a signal from which noise is cancelled to some extent is emphasized relative to the signal level in the noise band. Moreover, a cancellation factor is utilized in cancelling the noise, so that the voice level in the voice band is emphasized, or the noise level in the noise band is attenuated, achieving a better noise-suppressed voice signal.

Abstract: A noise-contained voice signal is cepstrum-analyzed to determine a peak and a mean-value thereof. When a peak is present, the signal is determined to be a vowel portion, and when a mean-value is large, the signal is determined to be a consonant portion, thereby allowing a voice portion to be accurately determined. Further, utilizing the detected result, noise is accurately canceled.

Abstract: A cepstrum calculating device obtains a cepstrum of a voice signal and a mean-value calculation device cepstrum means output. A threshold setting device sets a voice detection threshold level on the basis of the cepstrum mean-value output. A cepstrum addition section adds a cepstrum value exceeding the cepstrum mean-value. A comparator compares the cepstrum output from the cepstrum addition section with the threshold output signal from the threshold setting device, thereby to output a voice-detection signal.

Abstract: A signal processing unit separates voice signals and non-voice audio signals contained in a mixed audio signal. The mixed audio signal is channel divided, and the voice signal portions of the channel divided mixed audio signal are detected and extracted at one output. Non-voice audio signals contained in the voice signal portions are predicted based on the non-voice audio signal portions of the mixed audio signal. The thus predicted non-voice audio signals are combined with extracted non-voice audio signals to obtain continuous non-voice audio signals which are output at a second output. Alternately, instead of extracting the voice signals from the mixed audio signal, the predicted non-voice signals are removed from the mixed audio signal to obtain the voice signals which are output on the first output.